FM antennas are well known in the art. At times, certain FM channels are difficult to receive. There are various reasons for this difficulty. For example, the power of the signal from the transmitter may be low, the receiver may be a long distance away from the transmitter, or the path of the signal may be obstructed.
Conventional antennas are inadequate to address these problems for several reasons. Some conventional antennas are shaped to be omni-directional, such as in an S shape. They attempt to receive signals from many directions. However, when the antenna receives a selected signal from one direction, common multi-path signals from other directions interfere with this signal. This reduces the signal strength and/or introduces noise. Thus, for signals that are already difficult to receive, the antenna is inadequate. In addition to being omni-directional, some conventional antennas receive reflections of the signals from obstructions. These reflected signals also interfere with the original signal, reducing its strength.
Some conventional antennas attempt to compensate for these problems by being very large. However, these large antennas are cumbersome and are often expensive. Typically, they require guide wires to anchor them. Some conventional antennas include amplifiers in the antenna. However, the amplifiers, although potentially helpful with weak signals, can become overloaded by strong signals, resulting in intermodulation distortion. This causes many users to turn off the amplifier.
In addition, the effectiveness of many conventional antennas deteriorate over time. The antennas are manufactured with rivets and other similar fasteners, as well as other components which may be sensitive to the weather. For example, rust and other corrosion at the rivets results in the degradation of the selected signal and enhancement of noise to the overall reception. Also due to their sensitivity to the weather, many conventional antennas break or bend in strong wind.
Accordingly, there exists a need for an improved FM antenna. The antenna should be bi-directional, hermetically sealed, and of sturdy construction to withstand the elements over a significant period of time. The present invention addresses such a need.